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How Long Does A Septic Tank Last (PLUS 5 Tips To Make It Last Longer!)

how long does a septic tank last

How Long Does A Septic Tank Last: PLUS 5 Things That Make It Last Longer

Perhaps you’re in the process of buying an older home, or you have an older home, and the house has its own septic tank instead of being connected to the city sewer.  For one reason or another, you need to know how long septic tanks last. It could be that the home inspector listed it as an item to investigate further, or it might be that you’ve had your septic tank for year, and you just don’t think it’s working correctly.

As a homeowner, you need to know how long it’s going to be until you need to replace the septic system in the house.  This is important to know and understand because replacing the septic tank is not cheap.


So that’s the purpose of this post…to help you understand the life expectancy of your septic tank and know approximately how long it will last.  

To give you a quick answer, here are some rough guidelines for how long a septic tank might last, depending on what kind of system you have.  

For more detailed information on this…keep reading.

How Long Does A Septic Tank Last

The short answer is that a septic system can last anywhere from 15 to 40 years. The reason that it’s such a wide range is because there are many different factors that determine the life expectancy of a septic tank.

According to, “The life expectancy of a septic tank depends largely on its materials, while the life of septic system piping depends largely on the risk of damage from vehicle traffic, clogging by roots, or flooding by groundwater.”

Septic Tank Life Expectancy Based On System Type

How Long Do Steel Septic Tanks Last?  

A steel septic tank will eventually rust out depending on the acidity in the soil as well as the septic tank quality.  A steel septic tank that’s 15 to 20 years or older is probably already rusted to the point of having lost its baffles and possibly the tanks bottom.The cover on steel septic tanks will also last until it rusts out.  These areas of septic tank failure can easily be recognized by a professional during a routine septic tank inspection.

How Long Does A Concrete Septic Tank Last?  

A concrete septic tank can last from 40 years to forever if constructed out of high quality materials and designed well.  While poor quality concrete and acidic soils can cause the concrete septic tanks baffles and components to fail.

How Long Does a Leach Field Last?

According to, “A conventional septic drain field has a varying life as a function of the soil percolation rate, drainfield size, and usage level. I’ve seen a septic drainfield, a large one in good soil with a well maintained septic tank, last for more than 50 years. I’ve seen a conventional septic drainfield fail within 24 hours of first use on a new system when piping was poorly installed.”

The Largest Factor That Determines How Long A Septic Tanks Lasts

Septic Tank Service

Septic tank service is the most important thing you can do to help increase the longevity of your septic system. And keep in mind that septic tank pumping is only one part of septic service. 

Yes, you should have your septic tank pumped at least every three years or so, but there is more to septic tank service than simply pumping out the waste.

A quality septic tank service company will not just pump your tank, but they’ll also inspect the tank to and suggest any repairs or additional maintenance that should be done.. When a septic tank is pumped, all that’s really happening is the clear waste is being removed.  And what’s left in the tank is the solid scum that accumulates over the years. This “scum” also should be removed in order for the tank to continue to work correctly.

Having your septic system regularly serviced (just like a car, furnace or any other big ticket item you own) is the easiest way to increase its life.

How To Make A Septic Tank Last Longer

Some things that affect how long a septic tanks lasts are completely out of our control.  But there are some things we as homeowners can do to help prolong the life expectancy of our septic systems.  Some of those things are:

  1. Quality And Design:  Location, soil condition and installation will all contribute to the lifespan of not just your septic tank, but your entire septic system.  An overly wet location or one that’s prone to flooding will clog your leach field. Poor soil conditions, a high water table or surface water drainage into your leach field will also threaten the lifespan of your septic system. And even a poor septic tank installation can negatively affect the lifespan of your septic tank.
  2. Septic Tank Material: As mentioned above, concrete, plastic and fiberglass tanks can last 40 plus years. Steel tanks can rust away sooner than you would like.
  3. Septic Tank Workload: The overall workload on the septic tank and the leach field directly affects how long a septic tank lasts. Decreased use can increases the lifespan of the entire septic system as well as reduce the amount of maintenance required…which is also a big cost savings.  
  4. What Goes Into The Septic Tank: Flushing only water and waste and avoiding chemicals and non-biodegradable materials can also reduce the amount of waste build up inside your septic tank.
  5. Septic Tank Pumping And Service: Routines the solids before they have the chance to build up and clog your septic system. Regular nspections during the pumping process  can also extend the life of your septic tank because the professionals can catch problems while they’re still minor.

How Long Can A Septic System Sit Unused?

A septic system can sit unused for over 30 years. Remember, it’s all of the stuff we put into a septic system that ultimately plugs it up or degrades it and shortens it’s lifespan. If a septic system sits unused, and nothing is added to it, it should last as long as the concrete tank and the plastic leach lines do which is approximately 30 to 40 years.


There are many different things that determine how long a septic tank can last.  My septic tank is 46 years old and was just inspected this last year. And according to the pros, my old tank and system is still going strong.  But I’ll continue to do everything I can to make my septic tank and leach field last as long as possible. 

If you’re looking at purchasing a home with an older septic system, ask around…talk to the neighbors and see what their experience has been.  They share the same kind of soil and drainage, so they’ll know better than most.

The best piece of advice I’ve been given, and that I can pass on to you is, if a septic tank is at least 20 years old, then you should budget to have it replaced.  There’s a high possibility that the system will last you for years to come, but if you have the money put away, then it won’t be the financial blow that it otherwise would be had you not anticipated the septic tank replacement.

Taking care of the septic tank will extend the life of the tank and the leach field beyond the tank.  

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